Step 1: Understanding the Concept:
This question asks to identify the type of grain storage structure best suited for storing multiple different varieties of grain simultaneously, implying the need for compartmentalization.
Step 2: Detailed Explanation:
Let's analyze the suitability of each structure type for storing multiple varieties:
(A) Cylindrical grain bins: These are large, circular bins. While a farm or facility might have multiple cylindrical bins, a single bin is designed to hold one type of grain. It's difficult and inefficient to partition a cylindrical bin.
(B) Rectangular grain bins: Rectangular or square bins have flat walls. This geometry makes it very easy to construct internal dividing walls (partitions) to create multiple smaller compartments within a single large bin structure. This allows a facility to store several different varieties or grades of grain separately but within the same building, which is highly space-efficient. This is common in seed processing plants and research facilities where variety integrity is crucial.
(C) Pusa grain bins: This is a specific type of indoor storage bin developed in India for small-scale, on-farm storage. It's typically a single-compartment bin designed to be moisture and insect-proof, not for storing multiple varieties.
(D) Silos: A silo is a very large storage structure, typically cylindrical (either concrete or steel). Like cylindrical bins, a single silo is used for bulk storage of one commodity. A silo battery (a group of silos) can store different grains, but the individual structure is not designed for compartmentalization.
The key advantage of the rectangular shape is the ease of subdivision.
Step 3: Final Answer:
Rectangular grain bins are the most suitable structures for storing different varieties of grain because their shape allows for easy compartmentalization. Therefore, option (B) is the correct answer. The provided key has a check on option A, Cylindrical grain bins. This is generally incorrect. Rectangular bins are far more suited for subdivision. However, if the question implies a battery of separate bins, both could be used. But for a single structure, rectangular is superior. Let's assume the question means a group of bins. Even then, rectangular bins offer better space utilization when grouped. Given the ambiguity, the most technically correct answer for 'storing different varieties' implying subdivision is rectangular. The provided key may be incorrect or based on a different interpretation. I will adhere to the technical correctness.
{Correction based on provided key}: If the key insists on (A) Cylindrical grain bins, the reasoning might be that large-scale grain handling facilities prefer to use batteries of separate, free-standing cylindrical bins to store different varieties, as they are structurally more efficient for large volumes than rectangular bins. In this context, one would use multiple cylindrical bins. But the wording of the question does not make this clear.
Let's assume the most common interpretation.
Step 4: Final Answer based on Engineering principles:
Rectangular grain bins are the most suitable for subdivision to store multiple varieties in a compact space. Therefore, option (B) is the correct answer.